#include<bits/stdc++.h>
using namespace std;
#define int long long
struct Line{
	int l,r,pos;
	bool operator< (Line another) const {
		return pos<another.pos;
	}
} a[210000],b[210000];
int p[1100000];
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	freopen("lucky.in","r",stdin);
	freopen("lucky.out","w",stdout);
	
	int c,T;cin>>c>>T;
	while(T--){
		int n;cin>>n;
		int sl=0,sr=0;
		for(int i=1;i<=n;i++){
			cin>>a[i].l>>a[i].r>>a[i].pos>>b[i].pos;
			b[i].pos++;
			b[i].l=a[i].l;b[i].r=a[i].r;
			p[i*2-1]=a[i].pos;p[i*2]=b[i].pos;
			sl+=a[i].l;sr+=a[i].r;
		}
		sort(a+1,a+n+1);sort(b+1,b+n+1);sort(p+1,p+n*2+1);
		int m=unique(p+1,p+n*2+1)-p-1;
		int ls=0,rs=0,suml=0,sumr=0;
		int ida=1,idb=1,ans=0;
		for(int i=1;i<=m-1;i++){
			while(a[ida].pos==p[i]){
				suml+=a[ida].l;sumr+=a[ida].r;
				ida++;
			}
			while(b[idb].pos==p[i]){
				ls+=b[idb].l;rs+=b[idb].r;
				suml-=b[idb].l;sumr-=b[idb].r;
				idb++;
			}
//			cout<<p[i]<<" ";
			if((ls<(sr-rs)) and ((sl-suml-ls)<=rs+sumr) and (suml!=0)) ans+=p[i+1]-p[i];
//			cout<<ls<<" "<<rs<<" "<<suml<<" "<<sumr<<" "<<ans<<"\n";
			
		}
		cout<<ans<<'\n';
	}
	return 0;
}